The use of invertebrate organisms has become a mainstay of aging research, leading to the identification of hundreds of aging genes. Emphasizing the utility of these studies, at least some of these genes and pathways have conserved effects on longevity in mammals. In taking stock of the progress, it is clear that a new, more system wide approach is required to effective move forward. As we see it, there are two main questions that need to be answered: (1) Given that there are hundreds of aging genes, in which altered expression is associated with lifespan extension, in an organism, how many pathways do they represent and how can they be delineated?; (2) what are the mechanisms that drive aging in invertebrate aging models and are they conserved? This latter question has remained stubbornly refractory to a variety of approaches in the aging research field. With an eye toward answering these two questions, in this proposal three research groups with complementary expertise have joined forces to develop a comprehensive understanding of replicative aging in Saccharomyces cerevisiae using a combination of high throughput and state-of-the-art approaches. Dr. Kennedy (in collaboration with Dr. Matt Kaeberlein at the University of Washington) has just completed a genome-wide screen of yeast ORF knockouts for enhanced replicative lifespan. In Aim 1, we will develop the largest epistasis network of aging using the high-throughput capacity of the Kennedy lab to functionally assess which downstream pathways are required for lifespan extension in a set of representative yeast aging genes. In Aim 2, Dr. Li's research group will use a newly developed microfluidic system to determine the state of pathways purported to be involved in aging in the context of long-lived yeast mutants and in Aim 3, Dr. Brem's group will use RNA sequencing to develop a comprehensive gene expression analysis dataset in a range of long-lived mutants. These latter two approaches will help determine the cellular consequences of longevity mutants and by combing those with the epistasis studies in Aim 1, we will generate a comprehensive understanding of replicative aging, identifying the pathways involved and moving toward a mechanistic understanding of longevity. PUBLIC HEALTH RELEVANCE: Understanding the pathways that regulate aging is of critical importance to medical research. The field has come to understand that aging is the biggest risk factor in a range of chronic diseases that are principle causes of morbidity and mortality in the United States. Moreover, slowing aging in model organisms does not just extend lifespan but, more importantly, delays the onset and progression of these diseases. In this proposal, a key step forward, we take a comprehensive system-wide approach to understand aging in a commonly studied model organism: yeast. To date, studies in yeast have led in large part to the identification of two pathways (TOR and Sirtuins) that are among the most studied in mammals, lending strength to the hypothesis that the knowledge we gain from studies in yeast will be applicable to human aging.